Costello started designing as a child — drawing dresses on his bedroom walls — and was making custom pieces for the likes of Céline Dion and Jennifer Lopez out of his Palm Springs shop before most designers finish school. National audiences met him on the eighth season of Project Runway, where he placed fourth, and again on Project Runway All Stars, where he finished runner-up.
The Grammy stage made his name. After dressing Beyoncé in white lace for the 56th Annual Grammy Awards, he dressed her again and again, alongside Meghan Trainor, Alicia Keys and more — work now on display at the Grammy Museum at L.A. Live. His gowns for Lady Gaga on American Horror Story, designed with Lou Eyrich, shared in a Primetime Emmy win. In 2017 Palm Springs gave him a star on its Walk of Stars.